Need Help With Cultured Stone Scratch Coat

johnny bravo

can someone please help me. i'm redoing my fireplace with cultured stone and need some advice on doing the scratch coat. first of all do i need the lathe and if so how do i affix it the the concrete blocks? what type of mortar do i use. thanks for any advice, i told the wife this project would be done before santa arrived and i'm running out of time

stacker

1st off,if your masonry has been painted you will need to install metal lath.if you are going over brick or block that has not been painted then no lath will be required.

2nd,i will tell you how i do my stone and you can go from there.
i will scratch on a thin coat,filling all voids,covering an area of about 12-15 square feet.i will then apply a thicker coat of mud about 1/2-3/4 in over that area.then i butter the back of the stone i intend to lay.(not all stone needs to be buttered,but it will help the stone adhere,so i would recommend it)place the stone where you want it and push it into the thicker mud coat.pick up the next stone and repeat.after you have covered the area,grout,using a grout bag,and proceed to the next area.when the cement has dried enough to tool,use a wire brush on the joints and wisk broom the joints.

the mixture i use for my cement is one sack of mason cement to 17 shovels(square point) of clean mason sand,and one shovel of portland cement.

this is the same process i have used for 30 years with no problems.
good luck

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Tommy C

Johnny,

If the block is not painted, you can scratchcoat right over the block.

Or, you can use thin set, and adheer the stone directly to the bare block.

johnny bravo

thanks for the quick advice guys. the blocks are fresh so i wont buy the lathe. i'm also installing the same stone on a wall off of the fireplace and rather then drywall i hung perma base cement board. do i need to scratch coat this or can i put the stone right on. thanks again.

Tscarborough

Stone right on. I prefer thinset too over wall board and CMU.

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